In the United States in 2015, 16.2% of women ages 15-44 were ages 15-19, 34.8% were ages 20-29, 33.0% were ages 30-39, and 16.0% were ages 40-44.

The demographic distribution of women and children in a state, county or city can have an impact on the rates of birth outcomes in that area. When comparing the rates of health indicators between different geographic regions, these distributions should be considered.

Source

US Census Bureau. Population estimates based on bridged race categories released by the National Center for Health Statistics.